Effect of nitric oxide synthase inhibition on cardiovascular and hormonal regulation during pregnancy in the rat

2000 ◽  
Vol 78 (5) ◽  
pp. 423-427 ◽  
Author(s):  
Yunlong Zhang ◽  
Susan Kaufman
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Plasma Renin Activity ◽  
Plasma Volume ◽  
Atrial Natriuretic Factor ◽  
Plasma Renin ◽  
Renin Activity ◽  
Pregnant Rats ◽  
Oxide Synthase ◽  
In Pregnancy

Recent studies have shown that nitric oxide (NO) biosynthesis increases in pregnancy and that inhibition of nitric oxide synthase (NOS) induces some pathological processes characteristic of preeclampsia. The current project sought to study the effect of the NOS inhibitor Nω-nitro-L-arginine methyl ester (L-NAME, 10 µg·min-1, sc for 7 days) on plasma volume, plasma atrial natriuretic factor (ANF), plasma endothelin-1 (ET), and plasma renin activity (PRA) during gestation in conscious rats. NOS inhibition caused mean arterial pressure to increase in both virgin and 21-day pregnant rats. Plasma volume fell in the pregnant rats [L-NAME, 4.5 ± 0.3 mL·100 g-1 body wt. (n = 7) vs. D-NAME, 6.8 ± 0.2 mL·100 g-1 body wt. (n = 10); P < 0.05] but not in the virgin rats [L-NAME, 4.3 ± 0.1 mL·100 g-1 body wt. (n = 6) vs. D-NAME, 4.8 ± 0.2 mL·100 g-1 body wt. (n = 8)]. There was no effect of NOS inhibition on plasma ANF levels or PRA in either the virgin or pregnant rats. However, L-NAME did decrease plasma ET levels in the pregnant rats [L-NAME, 19.6 ± 1.6 pg·mL-1 (n = 8) vs. D-NAME, 11.6 ± 2.5 pg·mL-1 (n = 9); P < 0.05]. Our results confirm that NO is involved in cardiovascular homeostasis in pregnancy; NOS inhibition selectively reduces plasma volume in pregnant rats, thus mimicking a major pathophysiological perturbation of preeclampsia. However, it does not induce the hormonal changes characteristic of preeclampsia, namely the decrease in PRA and increase in plasma ET and ANF levels. Key words: plasma volume, preeclampsia, endothelin, atrial natriuretic factor, plasma renin activity.

Plasma Renin Activity, Blood Uric Acid and Plasma Volume in Pregnancy-Induced Hypertension

Nephron ◽  
1985 ◽  
Vol 40 (4) ◽  
pp. 429-432 ◽  
Author(s):  
P. Fievet ◽  
L. Pleskov ◽  
I. Desailly ◽  
A. Carayon ◽  
J.F. de Fremont ◽  
...  
Keyword(s):  
Uric Acid ◽  
Plasma Renin Activity ◽  
Plasma Volume ◽  
Plasma Renin ◽  
Renin Activity ◽  
Pregnancy Induced Hypertension ◽  
Induced Hypertension ◽  
Blood Uric Acid ◽  
In Pregnancy

scholarly journals Effect of Blockade of Nitric Oxide Synthesis on the Renin Secretory Response to Frusemide in Conscious Rabbits

1995 ◽  
Vol 88 (6) ◽  
pp. 657-663 ◽  
Author(s):  
Ian A. Reid ◽  
Lance Chou
Keyword(s):  
Nitric Oxide ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Nitric Oxide Synthase ◽  
Arterial Pressure ◽  
Plasma Renin Activity ◽  
Plasma Renin ◽  
Macula Densa ◽  
Renin Secretion ◽  
Oxide Synthase

1. The enzyme nitric oxide synthase is present in the macula densa and may participate in the control of renin secretion by the adjacent juxtaglomerular cells. In the present study, we investigated the effect of inhibiting nitric oxide synthase on the renin secretory response to frusemide, which stimulates renin secretion by blocking Na+-K+-2Cl− co-transport in the macula densa. 2. Injection of frusemide in 12 conscious rabbits elicited a transient increase in mean arterial pressure from 84 ± 2 to 92 ± 3 mmHg at 5 min (P < 0.01) and a sustained increase in heart rate from 246 ± 6 to 281 ± 10 beats/min at 45 min (P < 0.01). Plasma renin activity increased from 8.0 ± 1.2 to 14.3 ± 1.8, 12.4 ± 1.6 and 11.6 ± 1.5 pmol 2 h−1 ml−1 at 15, 30 and 45 min respectively (P < 0.01). There were no changes in plasma sodium and potassium concentrations or osmolality. 3. Inhibition of nitric oxide synthase with NG-nitro-l-arginine methyl ester increased mean arterial pressure by 9 mmHg, decreased heart rate and plasma renin activity, and markedly suppressed the renin response to frusemide (from 4.6 ± 0.7 to 7.6 ± 1.7, 4.7 ± 1.0 and 4.6 ± 0.7 pmol 2 h−1 ml−1 at 15, 30 and 45 min respectively). By contrast, infusion of an equipressor dose of phenylephrine did not suppress the renin response to frusemide. 4. Histochemical studies with the NADPH diaphorase technique confirmed the presence of nitric oxide synthase in the macula densa, and suggested that enzyme activity is increased by treatment with frusemide. 5. These results are consistent with a role for the l-arginine—nitric oxide pathway in the modulation of renin secretion by the macula densa.

Solitary Kidney and Ageing as Causes of Low Renin and Aldosterone Concentrations: Relevance to ‘Low-Renin’ Essential Hypertension

1976 ◽  
Vol 51 (s3) ◽  
pp. 177s-180s ◽  
Author(s):  
R. Gordon ◽  
Freda Doran ◽  
M. Thomas ◽  
Frances Thomas ◽  
P. Cheras
Keyword(s):  
Blood Pressure ◽  
Essential Hypertension ◽  
Plasma Renin Activity ◽  
Plasma Volume ◽  
Plasma Renin ◽  
Renin Activity ◽  
Dietary Sodium ◽  
Sodium Restriction ◽  
Normotensive Subjects ◽  
The Mean

1. As experimental models of reduced nephron population in man, (a) twelve men aged 15–32 years who had one kidney removed 1–13 years previously and (b) fourteen normotensive men aged 70–90 years were studied. Results were compared with those in eighteen normotensive men aged 18–28 years and eleven men aged 19–33 years with essential hypertension. 2. While the subjects followed a routine of normal diet and daily activity, measurements were made, after overnight recumbency and in the fasting state, of plasma volume and renin activity on one occasion in hospital and of blood pressure on five to fourteen occasions in the home. Blood pressure was also measured after standing for 2 min and plasma renin activity after 1 h standing, sitting or walking. Twenty-four hour urinary aldosterone excretion was also measured. 3. The measurements were repeated in the normotensive subjects and subjects in (a) and (b) above after 10 days of sodium-restricted diet (40 mmol of sodium/day). 4. The mean plasma renin activity (recumbent) in essential hypertensive subjects was higher than in normotensive subjects. In subjects of (a) and (b) above, it was lower than normotensive subjects, and was not increased by dietary sodium restriction in subjects of (a). 5. The mean aldosterone excretion level was lower in old normotensive subjects than in the other groups, and increased in each group after dietary sodium restriction. 6. Mean plasma volume/surface area was not different between the four groups and in normotensive, essential hypertensive and nephrectomized subjects but not subjects aged 70–90 years was negatively correlated with standing diastolic blood pressure.

Role of renal nerves in response to volume expansion in conscious newborn lambs

1989 ◽  
Vol 257 (6) ◽  
pp. R1519-R1525 ◽  
Author(s):  
F. G. Smith ◽  
T. Sato ◽  
O. J. McWeeny ◽  
L. Torres ◽  
J. E. Robillard
Keyword(s):  
Renal Function ◽  
Glomerular Filtration Rate ◽  
Plasma Renin Activity ◽  
Glomerular Filtration ◽  
Atrial Natriuretic Factor ◽  
Volume Expansion ◽  
Filtration Rate ◽  
Plasma Renin ◽  
Renin Activity ◽  
Renal Nerves

The present study was designed to determine the influence of renal nerves in mediating the renal response to volume expansion in conscious newborn lambs. Bilateral renal denervation (n = 9) or sham surgery (n = 14) was carried out in newborn lambs 3 to 4 days before performing experiments. Lambs were between 6 and 12 days of age when studied. Chronic denervation did not alter basal neonatal renal function nor renal hemodynamics. Volume expansion with isotonic saline equal to 5% of body weight was associated with a fall in hematocrit and an increase in mean arterial blood pressure, glomerular filtration rate, urine flow rate, and Na+ excretion in intact and denervated lambs. In intact lambs, atrial natriuretic factor increased from 98 +/- 28 to 176 +/- 48 ng/ml during volume expansion and remained elevated for 1 h after volume expansion. In addition, plasma renin activity fell from 21 +/- 5 to 8 +/- 1 ng.ml-1.h-1 and aldosterone levels fell from 160 +/- 24 to 59 +/- 7 pg/ml by 150 min after the start of volume expansion. Similar changes in atrial natriuretic factor, plasma renin activity, and aldosterone were observed in denervated lambs. However, the increase in glomerular filtration rate, Na+ excretion, and fractional excretion of Na+ after volume expansion were significantly less in denervated than in intact lambs. Thus, in the newborn, the renal nerves do not appear to play a role in influencing basal renal hemodynamics and renal function but, as in the adult, the renal sympathetic nervous system does play a role in regulating fluid and electrolyte excretion during hypervolemia.

Expression of nitric oxide synthase isoforms and detection of nitric oxide in rat placenta

2002 ◽  
Vol 282 (4) ◽  
pp. C762-C767 ◽  
Author(s):  
Tatsuya Takizawa ◽  
Hiroshi Yoshikawa ◽  
Miho Yamada ◽  
Hidetoshi Morita
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Pcr Analysis ◽  
No Production ◽  
Epr Spectrum ◽  
Pregnant Rats ◽  
Paramagnetic Resonance ◽  
Triplet Signal ◽  
Oxide Synthase ◽  
Nos Isoforms

Nitric oxide (NO) production in the rat placenta was monitored and quantified by electron paramagnetic resonance (EPR) spectroscopy with hemoglobin and an Fe- N-(dithiocarboxy)sarcosine (DTCS) complex as NO-trapping reagents. Expression of nitric oxide synthase (NOS) isoforms was also examined by quantitative RT-PCR analysis. The EPR spectrum of the placenta with hemoglobin trapping showed a three-line hyperfine structure ( g = 2.008 and a = 1.66-mT). The EPR signal was diminished after the placenta was homogenized or the NOS inhibitor l-NAME was administered to pregnant rats. Therefore, the specific signal was definitely identified as being derived from endogenous NO spin-trapped by hemoglobin, and the EPR spectrum showed that the NO adduct existed as a pentacoordinate α-NO heme species. The EPR spectrum of the placenta with Fe-DTCS trapping showed a triplet signal ( g = 2.038) derived from an NO-Fe-DTCS complex. The height of the triplet signal did not vary significantly with gestational stage during the last few days of gestation. At the gestational stages examined, the level of NOS II mRNA expression was significantly higher than that of NOS III mRNA. NOS II expression in term ( day 21.5) placenta was significantly increased compared with that in preterm ( day 19.5) placenta ( P < 0.01, n = 4 or 5). These results suggest that NOS II is the predominant producer of NO in the placenta and that NOS II-generated NO plays significant roles in the maintenance of placental functions immediately before birth.

Sign in / Sign up

Export Citation Format

Share Document